Mounting problems are quite common with Exchange databases, especially when underlying troubles like dirty shutdown state, missing log files, or corrupt EDB files exist. Dealing with “database not mounting” issue in a risk-free manner requires the expertise of a reliable third-party tool like Stellar Repair for Exchange.

We often receive requests for help from Exchange users who are facing the “unable to mount database” error. The error is not an uncommon sight when dealing with Exchange databases and there are several reasons prompting it. Likewise, there are tons of ways to deal with the error; but more often than not, such fixes prove to be more of hit and trial solutions rather than a sure-shot remedy.

Through this article let us try to understand the “unable to mount database (HR=0x80004005, EC=550)” error by uncovering the primary reasons behind it and also compare the manual and automated solutions for it.

3 Steps total

Step 1: Reasons behind Exchange “Unable to Mount Database” Error

By scouting through various technical forums and perusing the problems of varied users, we’ve come to the conclusion that the most common reasons that trigger this error are:

Many a times, preventing this error is entirely out of your hands. Naturally, since quite a few of the above mentioned triggers of the error cannot be predicted. Thus, staying prepared with ample relevant backups and handy tricks to bring the database back to consistent state is optimum.

Step 2: Common Fixes

As you would have noticed, every Exchange error has a unique error code associated with it. Here, we’re focusing on the one with error code (EC) -550. The reasons prompting this error have already been discussed in the previous section, however, depending upon the exact error code the solutions to the problem can vary slightly.

To resolve Exchange mounting error -550, follow the below mentioned solutions one by one. Proceed to the next fix only if the previous one doesn’t work.

1. Restore the database from the most relevant backup or rollback transaction log files to restore it.
2. Try to force mount the database once using /force option in the Exchange Management Console. If you have a good backup, you can also try the -acceptdataloss option on the mount database command.
3. Perform a soft recovery to bring the database to clean shutdown, then move the log files to a new location and try mounting again. Here are the steps:

a. Run the command ESEUTIL /mh "" to check database status
b. If the result says the database is in “Dirty Shutdown” state, run ESEUTIL /ml command on the transactions logs to check their conditions.
c. If the output is OK, run a soft recovery using the command ESEUTIL /r on the database to bring it to a consistent state.
d. When the process completes, restart ESM and check database status again using ESEUTIL /mh command as shown in step a.
e. If the result says the database is in “Clean Shutdown”, move all log files and checkpoint files to a different location and then try mounting the database.
4. Exclude the directories in which your database and log files exist from anti-virus scanning. Also try unlocking EDB files from system locks by using tools for the purpose.
5. Hard repair the database using ESEUTIL /p command. Here are the steps:

a. Backup the EDB, STM, and log files in their current state
b. Run ESEUTIL /p command on the database. This will check all db pages for errors and fix them if possible. However, you should be aware that this repair method comes with a fair share of data loss risk since the database pages that cannot be repaired are simply discarded to bring it to a consistent state.

Note: This method should be used only as a last resort since it can lead to substantial data loss. Moreover, it is very time consuming and needs a lot of disk space to execute successfully.
6. Use third-party EDB repair tool to repair database and bring it back online safely. This is probably the best solution if other methods are not working. Consider this option before resorting to hard repair (/r).

Step 3: Using third-party tool to fix Exchange mounting error -550

To overcome the hazards of manual methods like significant data loss, and requirements of sufficient time and enough disk space (more than twice the size of the database), we recommend using Stellar Repair for Exchange to find and fix problems within Exchange database files. This reliable third-party tool competently repairs corrupted EDB files to fight with tough errors including the unable to mount database (HR=0x80004005, EC=550) error.

The tool facilitates recovery of dismounted and offline EDB files and their restore to Live Exchange Server / Office 365. It also gives users the option to save emails from the EDB files in PST, MSG, EML, HTML, RTF & PDF formats. Time and again this utility has proved to be a sure-shot remedy for Exchange troubles for users across the world.

The best way forward…

Remember to always keep sufficient backups of your EDB and log files handy as you never know when they might be needed. Also, it can’t hurt to keep a copy of reliable tools like Stellar Repair for Exchange with you for situations wherein traditional methods of restoring Exchange database fail to work.